1. Field of the Invention
The subject invention relates to firearms and more specifically to mechanisms that minimize fouling of firing components.
2. Description of the Prior Art
Firearms typically include a receiver that houses several working components of the firearm, including firing components, with a barrel extending from the receiver. There are various classes of firearms that operate in different manners. One class of firearm utilizes a bolt carrier disposed in the receiver that is moveable between a firing position, from which a live round of ammunition can be fired, and a retracted position, from which a spent casing is ejected. The movement of the bolt carrier and ejection of the casing can be accomplished with a direct gas impingement system. Examples of direct gas impingement type firearms include the M16, the M4®, such as the M4® carbine, and the AR-15®, such as the AR-15® Platform.
Firearms having the direct gas impingement system typically include an ejection port defined by the receiver. Direct gas impingement systems route exhaust gases back through the firearm to move the bolt carrier toward a retracted position. In particular, after firing the firearm, the direct gas impingement system routes exhaust gases, including any associated debris, from the barrel, back through a return tube to the bolt carrier, and out the ejection port of the receiver.
Some firearms include an ejection port door for covering the ejection port to prevent debris from entering the receiver and fouling the firing components. The ejection port door automatically opens in response to firing the firearm and/or charging the firearm, i.e. loading a live round into a chamber of the barrel. However, the ejection port door must be manually moved to the closed position by a user to prevent debris from entering the ejection port and thus entering the receiver. Accordingly, during combat it is unlikely the user will consistently close the ejection port door after firing or charging the firearm, thereby allowing debris to foul the firing components and potentially cause the firearm to jam or fail.
The prior art has attempted to solve the problem of debris entering the ejection port. For example, U.S. Pat. No. 3,619,926 to Alday discloses a firearm having a receiver defining an ejection port window with a bolt assembly movably disposed within the receiver. The firearm further includes a cover plate coupled to the bolt assembly with the cover plate movable independently to the bolt assembly. Having the cover plate and the bolt assembly moving independently of each other in such a manner increases frictional wear between the components and thus increases the possibility of the cover plate and/or the bolt assembly failing. In addition, the system disclosed in Alday is relatively complicated and has additional moving parts that are prone to failure.
Therefore, there remains a need to develop a firearm having a mechanism that automatically blocks an ejection port when in a firing position and minimizes, if not eliminates, fouling of the firing components.